Great attention is recently drawn to metalo-phthalocyanines as electroconductive, photoconductive, and energy transducing materials, electrode materials, and catalysts because of the presence of a metal ion in a large .pi.-electron conjugated system. Blends of metalo-phthalocyanines and polymers may be readily molded into films or the like. It is thus believed that a wide variety of highly functional polymer materials may be designed with ease. Metalo-phthalocyanines, however, are less compatible with conventional polymers, for example, polyacrylates and less soluble in organic solvents such as toluene. It is very difficult to evenly disperse metalo-phthalocyanines in polymers and there are thus obtained polymer compositions having low conductance.
The inventors previously synthesized metalo-phthalocyanine tetracarboxylic acids having --COOH radicals attached to the benzene nuclei of the phthalocyanine ring for the purpose of improving solubility and compatibility as reported in H. Shirai et al., Makromol. Chem., 180, 2073(1979). These metalo-phthalocyanine tetracarboxylic acids, however, are still insufficient in both solubility and compatibility.
It was expected that these metalo-phthalocyanine tetracarboxylic acids might be esterified with alcohols into alkyl esters having improved solubility. Unfortunately, the metalo-phthalocyanine tetracarboxylic tetraalkyl esters did not exhibit satisfactory conductivity because the alkyl moieties attached to the benzene nuclei create steric hindrance to prevent planar phthalocyanine rings of adjacent molecules from lying close together.